Public packet-switched networks have recently supported voice communications. “Internet telephony” is one example of packet-switched telephony. In packet-switched telephony, a packet-switched network, such as the Internet, serves as a transportation medium for packets carrying voice data. Voice-over-Internet-Protocol (VoIP) is one example of a collection of standards and protocols used to support voice communications over packet-switched networks such as the Internet. Others have been developed as well. A common Internet telephony scheme involves a computer or other device that is capable of connecting to the Internet. A gateway from the Internet to the Public-Switched Telephone Network (PSTN) allows a user of the computer to communicate through the Internet and PSTN to a telephone subscriber at a telephone connected to the PSTN. Other configurations are also possible.
Numerous benefits may be realized through the use of packet-switched telephony. For example, calls may be less expensive because of the utilization of a packet-switched network, such as the Internet, to traverse distances around the world. This is in contrast to conventional telephone service, which typically involves tying up telephone circuits to connect calls. Thus, a user in one location may communicate with a telephone subscriber at a second location by transmitting voice data across the Internet to a gateway that is located near a telephone subscriber's location, in order to avoid paying some or all of the long distance fees that might otherwise be associated with making such a call. Another possible advantage of packet-switched telephony service is the convenient interfaces and features that may be offered in a packet-switched telephony system. For example, volume control, a video session, or an address book application may be implemented. Many Internet Telephony Service Providers (ITSPs) have been formed in order to provide these services. Examples of ITSPs include Go2Call.com, Net2Phone, DialPad, Maxcall, AccessPower, and others. Each ITSP generally has its own calling rate and fee structure and may require a download of client software.
The download requirements vary by ITSP, but in general they require an application, such as a Java applet, and telephony gateway protocol software to be downloaded onto the device that will be interfacing with the Internet. The Java applet contains a dialing application can be used by a device equipped with a Java-capable browser, such as Internet Explorer and Netscape.
Several Internet telephony gateway protocols are available, including H.323, Session Initiation Protocol (SIP), and Media Gateway Control Protocol (MGCP). International Telecommunications Union standard H.323 is the current standard for transmitting voice over the Internet. One of the limitations of using H.323 is its large size. Downloading an H.323 stack can take up to ten minutes depending on a user's modem speed.
It is common for protocol standards to evolve quickly. As the protocol standards change, the user must typically download an application supporting the new version of the standard, in order to be able to complete an Internet call. The user will be delayed in placing their Internet call for the time it takes to download the latest version of the telephony gateway protocol. This is an inconvenience to the user and a potential lost subscriber to the ITSP.
A user may also wish to access the Internet using a handheld device or a cellular phone. Memory in these devices is typically more limited than in personal computers. As a result, large downloads may cause memory problems, or may even be impossible. As the world becomes more mobile, the use of these devices will likely increase, which will likely further the demand for Internet telephony.